1. Technical Field
This invention relates to material feeders, and more particularly to a material feeder having a flexible rotary dispensing member.
2. Background Information
Material feeders are used to accurately dispense various materials in many fields. One application can be found in the handling of abrasive wheel components such as abrasive and bond particulate that is placed in molds to form abrasive grinding wheels. In this setting, a material feeder may be combined with a press system or mold filling system that includes a weighing scale. Adjusting the feed rate of material dispensing is used to effect precise material weigh out. One type of material feeder includes a hopper having an opening to allow material to flow therefrom to an adjacent rotary dispensing member that receives the material. The rotary dispensing member then dispenses the material to an adjacent area as it rotates. An example of this type feeder is disclosed in U.S. Pat. No. 3,873,652, which is incorporated herein by reference.
While these rotary material feeders are effective in many applications, they are limited in a number of ways by their restricted control of feed rate, or flow volume. In most feeders of this type, adjustment of the feed rate is provided by changing the speed of rotation of the rotary dispensing member only. Another way to adjust feed rate is to control the gap size between the hopper opening and the rotary dispensing member. Unfortunately, the gap size is oftentimes predetermined by the position of the feeder""s output shaft and the specific dispensing member chosen. In technologies where the amount of material required is very specific, e.g., in the manufacture of abrasive wheels, the resulting imprecision in the feed rate is a problem. A need to slowly diminish the feed rate is also not addressed by this type material feeder. In addition, these feeders suffer from a tendency to permit material to flow even after cessation of rotation of the dispensing member.
Another limitation is that the variety of material, and in particular the size of material, that a feeder can handle is restricted by the gap size between the hopper opening and specific rotary dispenser member used. Switching one dispensing member for another is time consuming and inconvenient, and adjustment of the position of the rotary dispensing member relative to the hopper opening requires complex and costly mechanisms.
One attempt to provide more accurate dispensing is disclosed in U.S. Pat. No. 5,551,492, which is incorporated herein by reference. This reference provides a rotary dispensing member having slots to receive a measured amount of material. While this system may provide more accurate dispensing, it does not provide continuous flow of material and requires a relatively complex construction. The system is also limited in that it has difficulty handling differing sized material and is difficult to clean.
Other material feeders that use vibration, augers or belts to feed material also have restrictive ranges of feed rate. These type feeders may also be difficult to clean between runs of different type material.
A need thus exists for an improved material feeder having a wide range of feed rate adjustability, ease of cleanup and accommodation of differing size materials.
According to an embodiment of this invention, a material feeder comprises a hopper having an opening, and a flexible rotary dispensing member positioned adjacent the opening. The flexible rotary dispensing member has an adjustable curvature that determines the gap distance between the member and hopper opening.
A second aspect of the invention provides a dispensing member for a rotary material feeder, the dispensing member being made of a flexible material.
The invention provides, in a third aspect, a method of operating a rotary material feeder having a hopper and a rotating dispensing member positioned adjacent an opening of the hopper, the method comprising the steps of: supplying material to the hopper, providing a flexible rotating dispensing member, adjusting a curvature of the rotating dispensing member, and rotating the flexible rotating dispensing member.
The above and other features and advantages of the invention will be more readily apparent from a reading of the following more detailed description of various aspects of the invention taken in conjunction with the accompanying drawings.